1. Field of the Invention
This invention relates in general to bilateral digital data communication and in particular to the transmission and reception over a pair of lines at different frequencies of phase shift keying (PSK) modulated signals utilizing a PSK modem for communication with digital data handling apparatus.
2. Description of the Prior Art
Discrete component bilateral digital data transmission systems are well known in the prior art. These systems include PSK type modem components.
Single semiconductor chip frequency shift keying (FSK) modems are known in the prior art. See, for example, copending patent application Ser. No. 269,214, filed June 2, 1981, entitled "Integrated Circuit FSK Modem" and assigned to the assignee of this invention. The FSK technique has certain disadvantages with respect to requiring a large band width and relatively slow data rates.
The PSK modem employed in this invention provides all of the necessary modulation, demodulation, and filtering functions on a single chip. The analog functions of the circuit are implemented using switched capacitor technology.